1. Field
Embodiments relate to an image forming apparatus and a control method thereof, which reduce a velocity change of a photoconductor, thereby achieving a reduced color registration error.
2. Description of the Related Art
Generally, an image forming apparatus is devised to form a color image, in which an electrostatic latent image is formed on a photoconductor as light scans the photoconductor that has been charged with a predetermined electric potential and, after the electrostatic latent image is developed using a desired color of toner, a developed toner image is transferred and fused to a sheet of paper.
An image forming apparatus contains various colors of toner, such as, e.g., Cyan, Magenta, Yellow, and Black toners, to realize a sense of color corresponding to input print data by color combination of the different colors of toner, whereby the image forming apparatus may print various colors of images. Differently from black-and-white printing, several colors may overlap one another on a surface during color printing. When printing a surface using several colors, various reasons may make it difficult to print each color at an accurate position, causing a color registration error. The color registration error may be confirmed via test printing of a color registration error detection pattern.
A photoconductor is not completely spherical and thus, has a periodic velocity change. There are several reasons behind such periodic velocity change, such as, e.g., a shape error as well as alignment and installation errors of the photoconductor, and structural and operational errors of a gear or a coupling connected to the photoconductor. The period velocity change of the photoconductor may be an immediate cause of the color registration error.
Accordingly, to minimize the periodic velocity change of the photoconductor so as to reduce the color registration error, it has been conventionally attempted to eliminate structural instability of the photoconductor, or to control, e.g., a tolerance of a gear member connected to the photoconductor.
However, since there is a limit to rotate the photoconductor at a constant velocity even if the structural instability is eliminated to some extent, it may be difficult to reduce the color registration error.